This invention relates to a system having a friction heater for heating the operator's cabin of a machine, such as a motor vehicle, powered by an internal combustion engine. The system includes a high-pressure feed pump located within the engine compartment of the internal combustion engine and capable of delivering its output under heat through a throttling element from the lubricating oil pan of the internal combustion engine, the oil being heated upon passing through the throttling element for heating the operator's cabin via a heat exchanger.